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M Kawata

Publications and source records attributed to M Kawata.

At least 109 records · Page 6Linked to original sources
PubMed1994

Region-specific changes of tyrosine hydroxylase-immunoreactivity by estrogen treatment in female rat hypothalamus.

The effect of 17 beta-estradiol (E2) treatment for 28 days on tyrosine hydroxylase-immunoreactive (TH-IR) neurons in the periventricular preoptic nucleus (PPN) and medial preoptic area (MPA) of ovariectomized (OVX) rats was examined by morphometric analysis. The number of TH-IR neurons in the PPN of the E2-treated group was smaller than that of the OVX group, whereas the opposite result was found in the MPA; the number of TH-IR neurons in the MPA of the E2-treated group was larger than that of the OVX group. Numerous TH-IR neurons were found in the ventromedial portion of the MPA of the E2-treated group. In both the OVX and E2-treated groups, TH-IR neurons contained many short processes up to 40 microns in length. E2 treatment caused a significant decrement of the number of neurons containing the processes in the range of 10-40 microns length in the PPN, however it caused a significant increment of the number of neurons containing the processes in the range of 5-10 microns length in the MPA. These results suggested that immunoreactivity of TH in the PPN and MPA neuron are affected by E2 treatment and that E2 might modulate the production of TH in a region-specific pattern within the hypothalamus of the female rat.

Animals↗
PubMed1994

The effects of NGF and glucocorticoid on the cytological features of rat chromaffin cells in vitro.

We investigated the effects of nerve growth factor (NGF) and glucocorticoid on the differentiation of rat chromaffin cells during development (postnatal day 0, 5, 10, 15, 25) in vitro, by evaluating four parameters of cytological alterations; the percentage of process-bearing cells, the number of primary processes, the number of branches per cell and the total length of processes. Cultures of dissociated chromaffin cells from each developmental stage were maintained in medium containing a combination of NGF and/or the synthetic glucocorticoid, dexamethasone (DEX). All parameters for neuronal differentiation were highest in chromaffin cells from P0 animals when incubated in NGF(+)/DEX(-), but lowest in those from animals at P25 incubated in NGF(-)/DEX(+). In addition, chromaffin cells became progressively insensitive to the effects of NGF on cytological differentiation from P0 to P25. These results suggest that as development proceeds locally-derived factors become less potent on chromaffin cell differentiation.

Animals↗
PubMed1994

Estrogen affects calcitonin gene-related peptide- and methionine-enkephalin-immunoreactive neuron in the female rat preoptic area.

The effects of estrogen on the neurons of the medial preoptic area of the ovariectomized rat were immunohistochemically investigated using antisera to calcitonin gene-related peptide (CGRP) and methionine-enkephalin (Met-Enk). To visualize CGRP- and Met-Enk-immunoreactive (IR) cell somata, colchicine was injected into the cerebroventricle. CGRP- and Met-Enk-IR neurons were distributed in the medial preoptic nucleus (MPN) but few in the periventricular preoptic nucleus (PPN) in the ovariectomized rat. After estrogen treatment, CGRP immunoreactivity was markedly increased in the PPN and MPN, whereas Met-Enk immunoreactivity was increased in the MPN. These results, along with our previous data, suggest that estrogen accelerates CGRP- and Met-Enk expression in a different manner in the PPN and MPN neurons.

Animals↗
PubMed1994

Steroid hormone effects on gene expression, neuronal structure, and differentiation.

Steroid hormones modify several functions of the nervous system by altering expression of particular genes that are relevant for cell-to-cell communication, neuronal structure, and differentiation. There are many regions of the brain showing structural differences between male and female. These sexual dimorphisms are primarily based on cytological features of the nervous system brought about by the organizational action of sex steroid hormones. Glucocorticoids also have a great influence on neuronal survival and differentiation. First, in this paper the estrogen effect on the phenotypic changes of neurons in the preoptic area in vivo was described, particularly in the neuronal system of methionine-enkephalin and calcitonin gene-related peptide. Second, the tissue culture system for the preoptic area was developed and the estrogen effect on process extension associated with cytoskeletal changes was examined. Third, glucocorticoid suppression of the differentiation of adrenal chromaffin cells and transmitter/neuropeptide plasticity was studied in the dissociated culture system. The results suggest that steroids modulate neurotransmitters and neuropeptides expression along with the alteration of cell structures in a different manner in a tissue-specific pattern.

Androgens↗
PubMed1994

Molecular changes of organelle DNA sequences in rice through dedifferentiation, long-term culture, or the morphogenesis process.

Callus-specific rearranged DNA in rice (Oryza sativa L.) was isolated by in-gel reassociation procedure. Southern hybridization experiments revealed that some clones were amplified significantly in primary callus induced from scutellum tissue. Rapid amplification of these clones was observed within 2 days after plating seeds onto callus-induction medium containing 2,4-D. NAA gave no significant effect on DNA amplification event. Colony formation process from isolated protoplasts and plant regeneration process from callus showed clone-specific and process-specific fluctuation patterns of copy number. Sequence analysis of the clones suggested that most of the clones were originated from organelle DNA. Comparison of copy number fluctuation pattern of organelle functional genes with that of the clones suggested multiformity and/or construction-specific amplification of organelle DNA.

Adenosine Triphosphatases↗
PubMed1994

Local secretion of corticotropin-releasing hormone by enterochromaffin cells in human colon.

BACKGROUND/AIMS: Corticotropin-releasing hormone (CRH) is a regulator of the hypothalamic-pituitary-adrenal axis and a coordinator of the gastrointestinal response to stress. In addition to its central effects, CRH has peripheral effects on the immune system. CRH is present in several human tissues, such as the brain, spinal cord, adrenal medulla, lung, liver, peripheral blood leukocytes, as well as the gastrointestinal tract. The current study examined the local production of CRH in the normal human colon. METHODS: Normal human colonic tissues obtained by endoscopic biopsy were immunostained with anti-CRH and anti-5-hydroxytryptamine antibody and analyzed for CRH messenger (m)RNA by a reverse-transcribed polymerase chain reaction method and by in situ hybridization. RESULTS: Immunoreactive CRH and CRH mRNA were detected in the colonic mucosal cells in the neighborhood of the base of the crypts. The mucosal cells that expressed CRH mRNA also immunostained with anti-5-hydroxytryptamine antibody. CONCLUSIONS: Normal human colonic mucosal enterochromaffin cells produce CRH. CRH in the colonic mucosa may play a role in the modulation of the intestinal immune system and/or other gastrointestinal functions basally during stressful conditions.

Adolescent↗
PubMed1994

Estrogen receptor-immunoreactive neurons contain calcitonin gene-related peptide, methionine-enkephalin or tyrosine hydroxylase in the female rat preoptic area.

We have shown in our previous studies that estrogen treatment selectively influences calcitonin gene-related peptide (CGRP)-, methionine-enkephalin (Met-Enk)- and tyrosine hydroxylase (TH)-immunoreactive (IR) intensities in the neurons of the periventricular preoptic nucleus (PPN) and the medial preoptic area (MPA) of the female rat. In the present study, we examined whether estrogen receptor (ER)-IR neurons in the PPN and MPA contain CGRP, Met-Enk, or TH using a double-labeling immunohistochemical method and investigated changes in the number of double-labeling cells upon treatment with estrogen. Brain sections of ovariectomized rats and ovariectomized and estrogen-treated rat were stained using the avidin-biotin-peroxidase complex method followed by the peroxidase-anti-peroxidase method. The sections were first incubated with an anti-ER antibody in conjunction with nickel diaminobenzidine which produces a dark blue reaction product in the nucleus. Subsequently, CGRP, Met-Enk or TH antisera were applied to these sections and the resulting brown diaminobenzidine reaction product in the cytoplasm was examined. Neurons that were double-labeled for ER and CGRP, Met-Enk or TH were investigated in the PPN and MPA. The number of doubly labeled ER/CGRP- and ER/TH-IR neurons was large, whereas the number of ER/Met-Enk-IR neurons was small. These results suggest that ER in the PPN and MPA may be more closely related to the mechanism of changes in CGRP- and TH-IR intensities upon estrogen treatment than that in Met-Enk-IR intensity.

Animals↗
PubMed1994

Utility of gastrointestinal physiology regulated-dogs: bioavailability study of a commercial sustained-release dosage form of theophylline.

The utility of gastrointestinal physiology regulated-dogs (regulated-dogs) was evaluated in a bioavailability study. The gastrointestinal physiology of beagle dogs was regulated with a combined-treatment of intramuscular pentagastrin and intravenous atropine sulfate. Theophylline has been regarded as a drug that is absorbed completely in the entire gastrointestinal tract but slowly in the colon for humans. A commercial sustained-release tablet (SR tablet) of theophylline and a commercial conventional tablet of aminophylline (theophylline hemiethilenediamine salt) were chosen as model preparations in this study. In the regulated-dogs, the drug absorption was almost complete for the conventional tablet. The bioavailability of the SR tablet accounted for 76% in the regulated-dogs and 71% in intact dogs relative to that of the conventional tablet in the regulated-dogs, respectively, but no significant difference was detectable between these values. An advantage of the regulated-dogs over the intact dogs was, however, revealed in the time-profiles of the cumulative percentage of theophylline absorbed from the SR tablet, suggesting a modification of drug absorption by the prolonged arrival of the tablet to the colon.

Animals↗
PubMed1994

Regeneration of serotonergic immunoreactive fibers in the brain of 5,6-dihydroxytryptamine treated rat.

After the intraventricular injection of 5,6-dihydroxytryptamine (5,6-DHT), the course of degeneration and regeneration of the serotonergic fibers in the rat brain was studied immunohistochemically by using serotonin antiserum. Three days after 5,6-DHT treatment, an extensive disappearance of serotonin immunoreactive fibers was observed throughout the brain. Degenerative serotonergic fibers characterized by droplet-like swelling and intense staining by serotonin antiserum were detected in the following discrete areas, e.g., medial forebrain bundle (MFB), cingulate cortex, septal nucleus, diagonal band of Broca (DBB), lateral preoptic area, bed nucleus of stria terminalis, perifornical area, stria-terminals, raphe nuclei, ventral tegmental area, periaqueductal gray lateral reticular nucleus and nucleus of the solitary tract. The swelling were regarded as the proximal stumps of the chemically injured serotonin fibers. Sprouting serotonin fibers emanating from these swellings were observed 5 days after injection. The swollen thick fibers were seen up to 3 months thereafter throughout the brain, although they gradually decreased in number until 1 month after injection. On the contrary, the sprouting fibers extended their terminal fields throughout the brain. Three types of reorganization pattern of regenerating serotonergic fibers were distinguished: hyperinnervation, normoinnervation (similar to the normal innervation) and hypoinnervation patterns. In the areas with hyperinnervation, the density of the serotonergic fibers gradually increased for 3 months. These hyperinnervation patterns of regenerative serotonergic fibers were observed in the MFB, cingulate cortex, diagonal band of Broca, perifornical area, raphe nuclei, ventral tegmental area, motor trigeminal nucleus, facial nucleus, lateral reticular nucleus, inferior olivary complex and hypoglossal nucleus. On the other hand, the hypoinnervation displayed by a few regenerating serotonergic fibers was observed in the periventricular part of the prosencephalon, the ventromedial part of the hypothalamus, the dorsal hippocampus, the neocortex, the superior and inferior colliculi, the cerebellum, the dorsal tegmental nucleus of Gudden, the vestibular nuclei, the gracile nucleus and the cuneate nucleus. These reorganization patterns were formed 3 months after injection, and continued for a long time (2 years). The mechanisms of serotonergic fiber reorganization are discussed.

5,6-Dihydroxytryptamine↗
PubMed1993

Enhanced expression of the mouse L-histidine decarboxylase gene with a combination of dexamethasone and 12-O-tetradecanoylphorbol-13-acetate.

We previously reported that the induction of L-histidine decarboxylase (HDC) in mouse mastocytoma cells was synergistically potentiated with a combination of dexamethasone and 12-O-tetradecanoylphorbol-13-acetate (TPA) [Biochim. Biophys. Acta, 1133, 172-178 (1992)]. To clarify the molecular mechanism of this synergistic action on HDC expression, we have isolated genomic DNA clone (MGH5), including 5'-flanking region of the mouse HDC gene. The transcription start site and the nucleotide sequences of the promoter regions were determined. We found that this clone contains a TATA-like box and a GC-box in the promoter region, and several putative binding sites for regulatory proteins in the 5'-flanking region. With mastocytoma cells transiently transfected with 5' deletion constructs of HDC-CAT fusion gene, it was found that the sequence from -267 to -43 is essential for the regulatory elements(s) involved in the increased transcription of the HDC gene with dexamethasone and TPA.

Amino Acid Sequence↗
PubMed1993

[The histochemical study of the effects of estrogen on the forebrain cholinergic neurons of fetal female rats transplanted into the anterior eye chamber of adult female rats].

In order to clarify the effects of estrogen on cholinergic basal forebrain neurons, a cholinergic neuron in the diagonal band nucleus of the female fetal rat was implanted into the anterior eye chamber of the female adult rat. Some host rats were treated with 2mg estradiol valerate (E2v) injected every 3 days after ovariectomy while others were not 2 and 4 weeks after transplantation, the growth of cholinergic neurons in the graft was studied using acethylcholinesterase (AChE) histochemistry. At 2 weeks after transplantation, AChE positive neurons and fibers were densely distributed in the grafts of E2v treated rats. Also in grafts without E2v treatment, AChE positive neurons and fibers were found in all the grafts although their density was low. At 4 weeks, AChE staining was dense staining observed in both groups. These results indicate that neurotrophic effect of estrogen on the cholinergic basal forebrain neurons.

Acetylcholinesterase↗
PubMed1993

Intraocular co-grafts of fetal dorsal raphe nucleus and suprachiasmatic nucleus.

Serotonergic neurons in the fetal dorsal raphe nucleus were grafted together with fetal anterior hypothalamic tissue including the suprachiasmatic nucleus (SCN) to the anterior eye chamber of adult rats. After 6 weeks transplantation, the double grafts were immunocytochemically examined using antisera against serotonin, arginine vasopressin (AVP) and vasoactive intestinal polypeptide (VIP). The raphe grafts contained a large number of serotonin-immunoreactive neurons and fibers, but only a few AVP-immunoreactive fibers and VIP-immunoreactive neurons and fibers. On the other hand, numerous AVP- and VIP-immunoreactive neurons and fibers were found in the SCN of the anterior hypothalamic graft. Outgrowing serotonin-immunoreactive fibers from the raphe tissue were densely distributed in the anterior hypothalamic graft. In the SCN, however, only a few fibers were detected. The results demonstrate that the isolated anterior hypothalamic grafts can be innervated by the serotonergic neurons from the raphe grafts, but the innervation pattern of these fibers was quite different from the normal rat. The present results indicate that the isolated SCN has an inhibitory influence on the growth of serotonergic fibers.

Animals↗
PubMed1993

Time-course analysis of changes in calcitonin gene-related peptide-and methionine-enkephalin-immunoreactivity in the female rat preoptic area after estrogen treatment.

The time-course effects of one month of estrogen upon calcitonin gene-related peptide - and methionine-enkephalin-immunoreactivity in the periventricular preoptic nucleus and medial preoptic nucleus were semi-quantitatively investigated with a computer-based image analysis system. Female Wistar rats were ovariectomized and implanted subcutaneously with a 10-mm-long silastic capsule containing estradiol-17 beta, or with a blank capsule, as a control. Estradiol-17 beta-treated rats were killed at days 1, 4, 7, 10, 14 and 28 after the implantation of estradiol-17 beta. To investigate the details of changes in calcitonin gene-related peptide- and methionine-enkephalin-immunoreactive fibers in the periventricular preoptic nucleus and medial preoptic nucleus, a grid, made up of 8 x 16 squares (one square corresponding to 50 x 50 microns in the true section), was set on the wall of the third ventricle, and immunoreactivity within each square was measured with an image analyser. In the control rats, calcitonin gene-related peptide- and methionine-enkephalin-immunoreactive fibers were distributed in the periventricular preoptic nucleus and medial preoptic nucleus. In the estradiol-17 beta-treated rats, calcitonin gene-related peptide-immunoreactive fibers increased prominently at day 1, day 7 and day 10 in the periventricular preoptic nucleus, whereas methionine-enkephalin-immunoreactive fibers increased at day 1, day 14 and day 28 in the periventricular preoptic nucleus and medial preoptic nucleus. These findings suggest that the mechanism underlying the increases in these calcitonin gene-related peptide- and methionine-enkephalin-immunoreactive fibers after estrogen treatment might be different.

Animals↗
PubMed1993

Vasopressin- and oxytocin-immunoreactive hypothalamic neurones of inbred polydipsic mice.

In the late 1950s the inbred polydipsic mice, STR/N, was discovered. The early studies indicated that the extreme polydipsia was not due to a lack of vasopressin but probably due to innate thirst of unknown origin. Because the recent investigation has revealed the presence of some functional abnormality in the brain of the STR/N mouse, we now investigated, using immunohistochemical techniques, distribution of vasopressin (AVP)- and oxytocin (OXT)-containing neurones in the hypothalamus of polydipsic strain of mouse and compared with that of the control. The pattern of distribution of AVP- and OXT-immunoreactive neurones in the paraventricular (PV), supraoptic (SO), and suprachiasmatic nuclei (SCN) of the STR/N polydipsic mouse was similar to that of the control, but the number of AVP-immunoreactive neurones was more numerous in the PVN and SON and less in the SCN in the polydipsic mouse than in the control. In addition, a discrete group of AVP- and OXT-containing neurones that was not clearly seen in the control was discovered in the STR/N. These results implicate that abnormal distribution in the brain AVP and OXT contribute to the mechanism responsible for the polydipsia shown by the strain STR/N.

Animals↗
PubMed1993

[An application of molecular cell biology to visualize and manipulate gene expressions of specific proteins in the neuroendocrine and pituitary systems].

Tremendous progress in molecular biology has made it possible to investigate the gene structure of proteins which maintain the internal environment of the living tissue. A wide variety of proteins is required for the diverse functions of the nervous and endocrine systems, because they contain a heterogeneous population of highly specialized cells. The proteins in the cell are all derived from specific genes which encode the sequences of amino acids through the process of gene expression. Four stages are involved in gene expression; transcription, processing of RNA, translation, and post-translational processing. In situ hybridization is a powerful technique to detect specific mRNA at the cellular level with microscopic resolution. Antisense method also has an impact upon gene expression. The basic idea of both in situ hybridization and antisense method is that nucleotides complementary to a specific mRNA will bind to the mRNA as a probe to detect its location or as an inhibitor to block processing or translation. In this paper, molecular cell biology, particularly in situ hybridization and antisense methods is described to localize the site of specific gene expression of biochemical messengers in the neuroendocrine and pituitary systems.

Animals↗
PubMed1993

Distribution pattern of c-Fos expression induced by sciatic nerve sectioning in the rat central nervous system.

c-Fos expression in the rat central nervous system following sciatic nerve section was compared using an immunohistochemical procedure with control skin-incisions. c-Fos-immunoreactive (IR) materials were localized in the nuclei of nerve cells, and these positive cells were most abundantly observed 120 min after the operation. In the spinal cord, c-Fos-IR cells were seen in the posterior horn on the operated, but not in the contralateral side. The anterior horn and the dorsal root ganglia did not contain c-Fos-IR cells. The experimental animals had the largest number of c-Fos-IR cells in the lumbosacral segments, especially in laminae I and II of L4 and L5 segments. The difference in the number of c-Fos-IR cells and IR intensity between the experimental and control animals was conspicuous in the lumbosacral segments, but there was no significant difference between them in the cervical and thoracic segments. In the brain, an apparent difference in positive cell distribution was not recognized between the experimental and control animals. c-Fos-IR cells were observed in various regions of the brain. A high concentration of positive cells was seen in the temporal cortex, the clastrum, the lateral septal nucleus (ventral part), the hypothalamic nuclei such as periventricular, suprachiasmatic, paraventricular, arcuate, dorsomedial and supramammillary nuclei, the paraventricular thalamic nucleus, the ventral lateral geniculate nucleus (magnocellular part), the pontine nuclei, the dorsal and dorsolateral tegmental nuclei, the parabrachial nucleus (Kölliker-Fuse nucleus), the locus coeruleus, and the nucleus of the solitary tract. Among them, the paraventricular and suprachiasmatic hypothalamic nuclei exhibited the most dense concentration of c-Fos-IR cells and intensity. These results indicate that the c-Fos expression in the brain is induced by transsynaptic stimulation. The findings that there was a clear difference in the distribution of c-Fos-IR cells and in intensity between the experimental and control animals in the lumbosacral segment of the spinal cord but not in the upper portion and the brain, suggested that there is poor discrimination of nociceptive information in the brain between stimulation by nerve section and skin-incision.

Animals↗